Two ways for dissipating heat from central processing units, or electronic elements. In one method, a plurality of fins and a fan are used to dissipating heats. In another method, a plurality of heat conductive tubes are used to guide heat from the electronic elements. The heat conductive tubes are connected to a heat-dissipating unit. However, this way is not suitable to be installed with a fan since the space is confined. Thereby, solder material is coated upon the connection of the heat conductive tubes and heat-dissipating unit. In manufacturing, they are placed in a vacuum furnace so that the solder material is permeated into the heat conductive tubes and heat-dissipating device. However, the whole manufacturing process is complicated and thus cost is high. Moreover, the solder material is harmful to human body and environments.
With reference to FIG. 1, the heat conductive tubes and heat-dissipating device are connected by tightening engagement. Each fin 10 has an axial hole 12 with a configuration corresponding to that of the heat conductive tube 11. The heat conductive tube 11 is positioned to a fixture (not shown). The shaped heat fins 10 are placed upon the heat conductive tubes 10. A shaping mold is used to punch the structure. Each fin needs one punching process so that each fin is connected to the heat conductive tube 11 tightly. However, since each time only one fin is punched, the time period is long and the process is complicated. Thereby, the vibration of the punching operation will make errors to the fins 10. Then the engagement of the heat conductive tubes 11 and fins 10 are affected so that gaps C1 generate (referring to FIG. 2). As a result yield ratio is high and then head convention from the heat conductive tube to heat-dissipating device is low. Thereby, there are many punching process being necessary in the process, and thus the shaping mold will wear and thus the lifetime is shortened.
Moreover, in the punching process, the surface of each heat conductive tubes is coated with oil. In punching, the oil will fill into the connecting surface connected the heat conductive tube due to capillary effect. This will induce the oxidization of the heat conductive tube 11 so as to reduce the heat conductivity of the heat conductive tube 11.